Legal claims defining the scope of protection. Each claim is shown in both the original legal language and a plain English translation.
1. A method in a power supply system, the power supply system receiving an input voltage and generating an output voltage on an output voltage node, the method comprising: providing a load switch circuit configured to connect, using a main switch, the input voltage to an output node of the load switch circuit in response to the load switch circuit being turned on; providing two or more power channels, each power channel coupled to the load switch circuit to receive the input voltage at the output node of the load switch circuit and each power channel coupled to the output voltage node of the power supply system to provide the output voltage, each power channel being configured as a buck converter and including at least a high-side power switch and a low-side power switch connected in series and an output inductor; enabling the main switch of the load switch circuit to connect the input voltage to the output node of the load switch circuit; measuring a current flowing through the main switch of the load switch circuit; determining that the current flowing through the main switch of the load switch circuit has exceeded a current limit threshold; and disabling the main switch of the load switch circuit in response to the determining and disabling the low-side power switch of each of the two or more power channels in response to the determining.
A power supply system regulates an input voltage to produce a stable output voltage. It uses a load switch with a main switch to initially connect the input voltage. Two or more power channels, each configured as a buck converter with high-side and low-side switches and an output inductor, draw power from the load switch's output. The system continuously measures the current through the load switch's main switch. If this current exceeds a predefined limit, the system immediately disables both the load switch's main switch and the low-side switch of each buck converter power channel to prevent damage.
2. The method of claim 1 , wherein enabling the main switch of the load switch circuit to connect the input voltage to the output node of the load switch circuit comprises: turning on the main switch to connect the input voltage to the output node of the load switch circuit.
The power supply system described previously activates the load switch by turning on its main switch, thereby connecting the input voltage to the output node that feeds the multiple buck converter power channels. This action allows the input voltage to reach the power channels, enabling them to begin converting the voltage to the desired output level. This explicit activation step ensures a controlled start-up sequence.
3. The method of claim 2 , wherein disabling the main switch of the load switch circuit comprises: turning off the main switch in response to the determining to disconnect the input voltage from the output node of the load switch circuit.
In the power supply system, when an overcurrent condition is detected, the main switch of the load switch is deactivated to disconnect the input voltage from the power channels. Specifically, the main switch is turned off, effectively isolating the power channels from the input voltage source to prevent further current flow and potential damage from the overcurrent fault.
4. The method of claim 3 , wherein turning off the main switch in response to the determining comprises: turning off the main switch in response to the determining within a time duration to avoid damage to the power supply system.
The action of turning off the load switch's main switch during an overcurrent situation happens very quickly. To protect the power supply, the main switch must be turned off within a specific, short timeframe to avoid damaging components due to excessive current. This speed is a crucial element of the fault tolerance mechanism.
5. The method of claim 3 , wherein turning off the main switch in response to the determining comprises: turning off the main switch in response to the determining within a time duration in the nano-seconds range.
The overcurrent protection in the power supply system turns off the main switch of the load switch extremely rapidly. The turn-off action occurs within nanoseconds of detecting the overcurrent condition. This ultra-fast response is required to minimize the stress on the components and prevent catastrophic failures.
6. The method of claim 1 , wherein the main switch of the load switch circuit further comprises a main switch input node coupled to the input voltage and a main switch output node being the output node of the load switch circuit and wherein measuring a current flowing through the main switch of the load switch circuit comprises measuring a current at the main switch output node as the current flowing through the main switch.
In the power supply system, the current measurement for overcurrent protection is taken directly at the output node of the main switch within the load switch circuit. The main switch connects the input voltage to this output node. Measuring the current specifically at this location provides an accurate indication of the current flowing through the switch itself, enabling precise overcurrent detection.
7. The method of claim 1 , wherein the main switch of the load switch circuit further comprises a main switch input node coupled to the input voltage and a main switch output node being the output node of the load switch circuit and wherein measuring a current flowing through the main switch of the load switch circuit comprises measuring a current flowing across the main switch input node and the main switch output node as the current flowing in the main switch.
In the power supply system, the current flowing through the main switch of the load switch is measured by monitoring the current between the input and output nodes of the switch. By measuring the current directly across the switch, the system accurately determines the amount of current flowing through the main switch itself for overcurrent detection purposes.
8. The method of claim 3 , wherein the main switch of the load switch circuit further comprises a main switch input node coupled to the input voltage, a main switch output node being the output node of the load switch circuit, and a control terminal; and wherein turning off the main switch in response to the determining to disconnect the input voltage from the output node of the load switch circuit comprises: turning off the main switch by driving the control terminal of the main switch in response to the determining to disconnect the input voltage from the output node of the load switch circuit.
The load switch in the power supply system has a main switch with input, output, and control terminals. To disconnect the input voltage during an overcurrent event, a signal is sent to the control terminal of the main switch, causing it to turn off and isolate the input voltage from the output node feeding the power channels. This control-terminal-driven shutdown provides a direct and reliable way to disable the switch.
9. The method of claim 8 , wherein the main switch comprises a first NMOS transistor having a drain terminal as the main switch input node, a source terminal as the main switch output node and a gate terminal as the control terminal; and the method further comprising: driving the gate terminal of the first NMOS transistor to a voltage value greater than a voltage value at the drain and source terminals of the first NMOS transistor in response to the main switch being turned on.
The main switch of the load switch in the power supply system is implemented using an NMOS transistor. The drain of the transistor is the input, the source is the output, and the gate is the control terminal. When the switch is on, the gate voltage is driven higher than both the drain and source voltages, allowing current to flow through the transistor and connect the input voltage to the load.
10. The method of claim 9 , wherein turning off the main switch in response to the determining to disconnect the input voltage from the output node of the load switch circuit comprises: driving the control terminal of the main switch using a second NMOS transistor to pull down on the control terminal of the main switch to turn off the main switch in response to the determining.
The NMOS transistor acting as the main switch in the load switch is turned off during an overcurrent event by using a second NMOS transistor to actively pull down the gate voltage of the main switch. This quickly reduces the gate voltage, cutting off current flow through the main switch and disconnecting the input voltage, thus protecting the system from overcurrent damage.
11. The method of claim 1 , further comprising: disabling the high-side power switch of each of the two or more power channels in response to the determining.
In the power supply system, in addition to disabling the low-side switches of the buck converters when an overcurrent condition is detected, the high-side switches of those same buck converters are also disabled. Disabling both high-side and low-side switches ensures that the buck converters stop switching immediately, preventing any further power delivery and contributing to the overall fault protection strategy.
Unknown
December 19, 2017
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